1. Field of the Invention
The present invention relates to an image recording apparatus for recording an image on a recording medium by ejecting droplets of a liquid.
2. Description of Related Art
An ink-jet head of an ink-jet printer has a common ink chamber communicating with a supply port through which an ink is supplied, and a plurality of individual ink passages which extend from outlet ports of the common ink chamber to respective nozzles open in an ink ejecting surface, through respective pressure chambers. A droplet of the ink is ejected from each nozzle when the ink in the corresponding pressure chamber is pressurized by a pulsation pressure wave. Air bubbles and foreign matters present in flow passages formed within the ink-jet head prevent normal propagation of the pulsation pressure wave applied to the ink in the pressure chambers, giving rise to a risk of deterioration of ink ejection characteristics of the ink-jet head. To overcome this drawback, there is known a technique of supplying the ink from the supply port to the nozzles, for the purpose of removing the air bubbles and foreign matters together with the ink ejected from the nozzles, and then wiping an ink ejecting surface of the ink-jet head with a wiping member, to remove the ink remaining on the ink ejecting surface. An example of this technique is disclosed in JP-2005-335303A.
According to the technique described above, the wiping member is moved in contact with the ink ejecting surface in the longitudinal direction of the ink ejecting surface, for wiping the ink ejecting surface. Generally, a negative pressure is generated within the nozzles due to a water head pressure, so that the ink which remains on the ink ejecting surface of the ink-jet head after the ink is ejected from the nozzles and until the wiping operation on the ink ejecting surface by the wiping member is performed tends to be sucked back into the nozzles as the time elapses. Consequently, the air bubbles and foreign matters once ejected together with the ink and remaining adjacent to the openings of the nozzles may be sucked back into the nozzles together with the ink. To prevent the once ejected air bubbles and foreign matters from being sucked back into the nozzles, a large volume of the ink must be ejected from the nozzles so that the ejected air bubbles and foreign matters are moved by a sufficient distance away from the openings of the nozzles, whereby the ink is considerably wasted for maintenance of the ink-jet head.